My comments at bottom.
--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:
Hi!
Some one once mentioned , thumbrule for xtal matching was within 10%
of the required BW. However I try to keep it within 100hz for SSB filters.
Till date all appear to have worked fine.
73
Rahul VU3WJM
PS: I make the BFO first and with 33pf in series with xtal measure
all available with me. Select ones within 100hz of each other . Take
the lowest one for carrier osc for BITX , takes care of xtal pulling.
This is a good thing to do. Having done lower sideband by picking
a high crystal makes pulling it high easier.
One other trick. Using the BFO to pick the crystals is a good first
step. Once the filter is fabricated you can use the BFO to sweep the
filter to assess the filter shape and bandwidth. Usually that
requires tacking on a coil and larger tuning capacitor temporarily.
Allison
KB1GMX
